I'm on Ubuntu 18.04 and since today whenever I lock my system and try to log back in using my password, it shows the 'in progress' spinner for few seconds then I get the error message "Authentication error". I can successfully log in on the first start though.
I have tried to force disable Wayland by uncommenting the line
/etc/gdm3/custom.conf but it had no effect. I was originally using Xorg as well.
I've checked for any available system updates in hope of getting a fix but none are available. What can I do to investigate into and fix this error?
Update: I re-installed Ubuntu 18.04 to get rid of the issue.